Model comparison
GPT-5.3 Codex vs Nemotron Ultra 253B
Head-to-head evidence from 11 shared benchmark results across 5 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.3 Codex #26 (Supported); Nemotron Ultra 253B #150 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.3 Codex and Nemotron Ultra 253B share 11 comparable benchmark results. 0 of 8 categories are comparable. 10 results are unique to GPT-5.3 Codex; 0 to Nemotron Ultra 253B.
Updated July 20, 2026- Shared results
- 11
- GPT-5.3 Codex only
- 10
- Nemotron Ultra 253B only
- 0
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.3 Codex and Nemotron Ultra 253B is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 11 shared benchmark results across 5 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
GPT-5.3 Codex is priced at $1.75 input / $14.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for Nemotron Ultra 253B. GPT-5.3 Codex has the larger context window at 400K, compared with 32K for Nemotron Ultra 253B.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | GPT-5.3 Codex | Δ | Nemotron Ultra 253B |
|---|---|---|---|
| Agentic | GPT-5.3 Codex71.4 | MarginNo overlap | Nemotron Ultra 253BNot measured |
| Coding | GPT-5.3 Codex67.2 | MarginNo overlap | Nemotron Ultra 253BNot measured |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.3 Codex | Nemotron Ultra 253B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.3 Codex$1.75 input / $14 output | Nemotron Ultra 253B$0 input / $0 output | Nemotron Ultra 253B has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.3 Codex79 tok/s | Nemotron Ultra 253BNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.3 Codex88.26 s | Nemotron Ultra 253BNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.3 Codex400K | Nemotron Ultra 253B32K | GPT-5.3 Codex lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding5 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | GPT-5.3 Codex | Nemotron Ultra 253B | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 44.3% | 9.1% | GPT-5.3 Codex leads |
| AA-GPQA DiamondSource | 91.5% | 72.8% | GPT-5.3 Codex leads |
| AA-HLESource | 39.9% | 8.1% | GPT-5.3 Codex leads |
| AA-Omniscience IndexSource | 9.9% | -45.5% | GPT-5.3 Codex leads |
| AA-Omniscience AccuracySource | 51.8% | 19.9% | GPT-5.3 Codex leads |
| AA-Omniscience Hallucination RateSource | 86.9% | 81.7% | Nemotron Ultra 253B leads |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | GPT-5.3 Codex | Nemotron Ultra 253B | Result |
|---|---|---|---|
| AA-IFBenchSource | 75.4% | 38.2% | GPT-5.3 Codex leads |
Frequently Asked Questions (3)
Can I compare GPT-5.3 Codex and Nemotron Ultra 253B on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for GPT-5.3 Codex and Nemotron Ultra 253B today?
GPT-5.3 Codex: $1.75 input / $14.00 output per 1M tokens Nemotron Ultra 253B: $0.00 input / $0.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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